The inside of your nose is called the nasal cavity. A mucous membrane lines your nasal cavity and it helps keep your nose moist. Little hairs inside your nasal cavity help filter the air you breathe in and block dirt and dust from getting into your lungs.
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A. Immune system
It helps our bodies fight everything that comes in our path.
A good index fossil is one with four characteristics: it is distinctive, widespread, abundant, and limited in geologic time. Because most fossil-bearing rocks formed in the ocean, the major index fossils are marine organisms
Answer: B
Explanation:
Ammonia is so toxic that it can be transported and excreted only in large volumes of very dilute solution. As a result most terrestrial animals simply don't have access to sufficient water to routine excrete ammonia.
The main advantage of urea is its very low toxicity. Animals can transport urea in the circulatory system and store it safely in high concentrations. Also much less water is loss when a given quantity of nitrogen is excreted in a concentrated solution of urea than would be in a dilute solution of ammonia.